1 / 31

Chapter 14

Chapter 14. Cooling System. Objectives. Analyze wear and damage to cooling system parts Explain cooling system theory Select and perform most appropriate repairs to cooling system. Types of Cooling Systems. Smaller engines are cooled by air only

oreyes
Download Presentation

Chapter 14

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 14 Cooling System

  2. Objectives • Analyze wear and damage to cooling system parts • Explain cooling system theory • Select and perform most appropriate repairs to cooling system

  3. Types of Cooling Systems • Smaller engines are cooled by air only • Most automotive cooling systems use liquid coolant • Engine block and cylinder head have cast-in water jackets

  4. Cooling System Parts • Water pump or coolant pump • Radiator • Radiator hose • The fan • Thermostat • Coolant

  5. Coolant Pump • Typically called a water pump • Impeller type pump • Mounted on front of engine and belt-driven • Aluminum or cast iron • Shaft supported by a bearing and uses a spring loaded front seal

  6. Coolant Pump

  7. Coolant Pump Failure • Static Seal • Coolant leaks from coolant vent hole • Bearing • Will also damage static seal • Impeller • Broken pieces of impeller can enter the block, and possibly the radiator • Pump plate leakage

  8. Possible Reasons for Pump Failure • High engine miles • Engine ran low on coolant • Out of balance fan assembly • Faulty fan spacer

  9. Belt Materials • Tensile chords provide strength • V-ribbed belts ribbed on one side and flat on the other • Thickness of v-ribbed belt allows it to wrap around smaller pulleys as well as bend backwards • This allow both sides to transmit power

  10. Accessory Drive Belt Service • Check all belts for wear, cracks, or damage • Replace glazed belt • Check for proper belt alignment

  11. Drive Belt Service

  12. Thermostats • Allows engine to warm up and maintain a constant temperature • Made of brass or stainless steel • Expansive wax compound expands at predictable rate to open valve • Rated according to engine temperature

  13. Radiators • Cross flow or down flow style • Coolant flows through radiator cores • Cores are constructed from copper or aluminum • Aluminum radiator cores conduct heat better than copper • Plugged radiator will cause overheating

  14. Heater Core • Heat exchanger located inside passenger compartment • Heat is transferred form engine into heater core then into vehicle • Core can leak or become plugged • Constructed of aluminum, copper, or brass

  15. Hoses • Consist of inner rubber tube, reinforcement, and outer rubber cover • Have a burst strength five to six times the normal operating pressure

  16. Hoses • 3 types • Straight • Molded • Universal

  17. Cooling System Pressure Cap • Putting system under pressure raises boiling point of coolant • Each pound of pressure raises boiling point three degrees • Cap includes a valve that allows coolant back into radiator as temperature drops

  18. Radiator Pressure Cap

  19. Radiator Fan • Draws air through radiator at idle and low speeds • Aluminum, plastic, or steel blades • Most late model vehicles use a fan driven by an electric motor • Some rear wheel drive vehicles still use belt driven fans

  20. Coolant Additives • Borax • Phosphate • Sodium molybdate • Sodium silicate • Sodium nitrate • Triazoles

  21. Coolant Additives • Sodium hydroxide • Phosphorescent • Benzoate • Water

  22. Electrolysis • Destructive to engine cooling system • Three types • Chemical electrolysis • Coolant has become too acidic • Caused from dissimilar metals in cooling system • Faulty electrical ground • Static electricity

  23. Checking Coolant Conductivity • Ground positive probe by grounding it to radiator • Insert negative lead into coolant • Reading should be .2 volts or less • If reading is .5 volts or more • System should be flushed and refilled with new coolant

  24. Checking Coolant Conductivity

  25. Testing Coolant Condition and Strength • Test strips can check pH, cavitation additive protection, and coolant concentration • Conventional coolant has a higher pH than extended coolant

  26. Testing Coolant Condition and Strength • Used conventional coolant should have a pH level of at least 9 • Extended life should be at least 7.5

  27. Testing Coolant Condition and Strength

  28. Coolant Density Testers • Two ways to test density: • Hydrometer Compares weight of ethylene glycol to weight of pure water • Refractometer Measures how much light can be bent by coolant

  29. Coolant Density Testers

  30. Coolant System Air Bleeding • All air must be removed from system • Jack front of car up as high as it will go • Some vehicles have bleed screws • Remove heater hose to bleed air • Use special air removal tool

  31. Cavitation • Causes of formation of air bubbles in coolant • Coolant boiling • Air in coolant • Suction restriction • Over pumping • Vibration of cylinder wall during combustion

More Related